This project is concerned with investigating the mechanisms responsible for the genesis of myopia and eye enlargement that are caused by neonatal lid fusion in macaque monkeys. The various components of the refractive state will be measured. Experiments are designed to analyze the effect of: (a) light, (b) form depreivation, (c) accommodation, (d) mechanical pressure on the globe, and (e) temperature on the myopia and eye elongation caused by neonatal lid fusion. Experiments will be carried out attemting to prevent the development of myopia in monkeys by means of pharmacological agents.